Hereinafter, other purposes, characteristics and other beneficial features of the present invention will become apparent from the following detailed description with reference to illustrative examples, taken in conjunction with the accompanying drawings.

Exemplary embodiments of the present invention to achieve the above objects will be described in detail in the following description with reference to the accompanying drawings.

In order to clarify a number of layers and/or regions in a plasma display panel, a thickness of each layer is enlarged in the drawings. Therefore, a thickness ratio between adjacent layers shown in the drawings is not to be construed as a true thickness ratio.

FIG. 1 is a constructional view illustrating a plasma display panel according to an exemplary embodiment of the present invention.

As illustrated in FIG. 1, a plasma display panel of the present invention comprises a front substrate 170 wherein a scan electrode 180a and a sustain electrode 180b, which both are made of indium tin oxide (ITO), as well as bus electrodes 180a and 180b made of common metal materials may be formed in a single direction on the front substrate 170.

A first dielectric layer 190 and a protective film are formed on the front substrate in this order while covering the scan electrode, the sustain electrode and the bus electrodes.

The front substrate 170 may be formed by milling and/or cleaning a glass material used for a display panel.

The scan electrode 180a and the sustain electrode 180b may be formed by photo-etching ITO or SnO ₂ through sputtering and/or by a lift-off process through CVD.

The bus electrodes 180a and 180b may contain Ag. Each of the scan electrode and the sustain electrode may have a black matrix, which comprises a low melting point glass and a black pigment.

A first dielectric layer 190 may be formed on the front substrate 170 on which the scan electrode, the sustain electrode and the bus electrodes are provided. The first dielectric layer 190 may include a low melting point transparent glass with a specific constitutional composition described below.

Also, a protective film 195 may be formed on the first dielectric layer 190.

Such protective film 195 may comprise MgO and zeolite. MgO used herein shows excellent orientation and crystalline properties which in turn increases a density of the protective film so as to fabricate a protective film with improved anti-sputtering properties. Zeolite is generally represented by Formula 1:

Formula 1

M ₂ O ₃ Al ₂ O _3x (SiO) _y (H ₂ O)

wherein M may be an alkali metal, alkali-earth metal or transition metal.

In Formula 1, x and/or y may determine what kind of zeolite is used. For the exemplary embodiment of the present invention, at least one selected from a group consisting of zeolite A, zeolite x, zeolite y, ZSM-5, ZSM-11, mordenite and chabazite may be used.

Using zeolite with SAR in the range of 1 to 500 may endow excellent film characteristics to the protective film 195. Especially, the protective film 195 exhibits the most excellent film characteristics with zeolite having SAR in the range of 300 to 400.

Such SAR means a molar ratio of SiO ₂ to Al ₂ O ₃ and may be higher with an increase in moles of SiO ₂ .

As shown in drawings, the protective film 195 may have a first layer 196 containing MgO and a second layer 198 containing zeolite.

The first layer 196 is a layer formed on the first dielectric layer 190 while the second layer 198 is a layer formed on the first layer 196 to face a discharge space.

Other than MgO, the first layer 196 containing MgO may be further doped with a dopant comprising at least one selected from a group consisting of SiO ₂ , TiO ₂ , Y ₂ O ₃ , ZrO ₂ , Ta ₂ O ₅ , ZnO, La ₂ O ₃ , CeO ₂ , Eu ₂ O ₃ and Gd ₂ O ₃ , each of which has a high secondary electron emission coefficient, and/or other oxides of transition metals, alkali metals or alkali-earth metals, so as to increase secondary electron emission.

Such dopant serves to increase secondary electron emission and an amount of the dopant preferably ranges from 0.001 to 10 wt.% in the first layer 196.

Adding the dopant to the first layer 196 can reduce a jitter value (variance in packet delays) during addressing. However, if a content of the dopant increases over a certain level, the jitter value may increase. Therefore, the dopant is preferably doped in a certain amount effective to minimize the jitter value and the optimal content of the dopant for this purpose may range 20 to 500 ppm (parts per million) in the first layer 196.

The first layer 196 may have a thickness of 300 to 700nm. If the thickness of the first layer 196 is less than 300nm, undesired discharge may occur. On the other hand, if the thickness exceeds 700nm, there may be problems in production process and/or economical disadvantages.

The second layer 198 may be formed on the first layer 196.

The second layer 198 may comprise zeolite. In this regard, the zeolite used in the second layer may have the same characteristics as disclosed above. The second layer 198 may be coated in a thin film form on the first layer 196. The thin film type second layer 198 preferably has a thickness in the range of 100 to 500nm.

On a surface of the back substrate 110, an address electrode 120 is partially formed in a direction crossing the sustain electrode pair. In addition, a white second dielectric layer 130 is formed throughout the surface of the back substrate while covering the address electrode 120.

Referring to FIG. 3, a detailed description will be given for constitutional compositions of the second dielectric layer 130 below.

The second dielectric layer 130 may comprise a low melting-point glass 132 and a filler 134 and, in the exemplary embodiment of the present invention, may further include zeolite 136 and nanometal oxide 138.

The melting-point glass 132 may be classified into lead containing parent glass and unleaded parent glass. The lead containing parent glass may comprise ZnO, PbO and B ₂ O ₃ , while the leaded parent glass may comprise ZnO, B ₂ O ₃ , BaO, SrO and CaO. The filler 134 may include carbon compounds such as SiC, nitrogen compounds such as BN, carbon nanotubes, and the like.

According to the exemplary embodiment of the present invention, the zeolite 136 may be at least one selected from a group consisting of zeolite A, zeolite x, zeolite y, ZSM-5, ZSM-11, mordenite and chabazite.

The zeolite 136 may have SAR in the range of 1 to 500, preferably, 300 to 400, in order to attain excellent film characteristics of the dielectric layer. SAR is known as a molar ratio of SiO ₂ to Al ₂ O ₃ and may be higher with an increase in moles of SiO ₂ .

The nanometal oxide 138 may be at least one selected from a group consisting of Al ₂ O ₃ , 3Al ₂ O ₃ 2SiO ₂ , Al ₂ O ₃ ZrO ₂ , Al ₂ O ₃ ZrO ₄ ZrO ₂ , TiSiO ₄ , Al ₂ O ₃ TiO ₂ , MgO and SiO ₂ .

The nanometal oxide 138 may have a size in the range of 10 to 1,000nm. If the size is too small, the nanometal oxide 138 may hardly react with the zeolite 136 and may coagulate to reduce dispersion thereof. On the contrary, if the size is too large, microfine pores may be formed throughout the back plate and/or there may be a problem in patterning the plasma display panel.

The zeolite may function as an excellent pyrolysis catalyst and have superior adsorptive and pyrolytic properties, thus exhibiting high reactivity.

The dielectric layer 130 may be applied to the back substrate by printing or green sheet laminating and may be completed by a firing process after drying.

At least one barrier rib 140 is arranged between adjacent address electrodes 120 above the dielectric layer 130. Such a barrier rib 140 may include stripe type, well type and/or delta type ribs.

Here, the barrier rib 140 may comprise a low-melting point glass and a filler and, in the exemplary embodiment of the present invention, may further include zeolite and nanometal oxide. Contents and/or characteristics of the zeolite and the nanometal oxide are substantially the same as disclosed above.

Red (R), green (G) and blue (B) phosphor layers (150a, 150b, 150c) are formed between adjacent barrier ribs 140, respectively. Intersection points between the address electrode 120 on the back substrate 110 and the sustain electrode pair on the front substrate 110 may construct discharge cells.

In this case, the phosphor layer 150 may comprise individual phosphor substances 150a, 150b and 150c and, in the exemplary embodiment of the present invention, may further include zeolite and nanometal oxide. Contents and/or characteristics of the zeolite and the nanometal oxide are substantially the same as disclosed above.

The front substrate 170 is combined with the back substrate 110 by interposing the barrier rib 140 therebetween and using a sealant provided around an outer side of the substrates.

The front substrate 170 and the back substrate 110 may be connected to a driving device.

FIG. 4 illustrates a driving device and a connection part of a plasma display panel according to the present invention.

As illustrated in FIG. 4, the whole plasma display device 210 of the present invention may include a panel 220, a driving substrate 230, and a tape carrier package (hereinafter, referred to as "TCP") 240 which is a flexible substrate to connect a plurality of electrodes placed in cells of the panel 220 to the driving substrate 230.

The panel 220 comprises the front substrate 170, the back substrate 110 and the barrier rib 140, as described above.

Electrical and physical connection of the panel 220 to the TCP 240 and electrical and physical connection of the TCP 240 to the driving substrate 230 may be embodied using an anisotropic conductive film (hereinafter, referred to as ACF").

The ACF is a conductive resin film prepared using a nickel (Ni) ball coated with gold (Au).

FIG. 5 illustrates a wiring structure of a substrate for a tape carrier package according to the present invention.

As illustrated in FIG. 5, a TCP 240 serves to connect the panel 220 and the driving substrate 230 and has a driver chip mounted thereon.

More particularly, the TCP 240 comprises a wiring 243 compactly arranged on the flexible substrate 242 and a driver chip 241 connected to the wiring 243, which receives electric power from the driving substrate 230 and supplies the electric power to a particular electrode mounted on the panel 220.

The driver chip 241 has a specific structure of receiving applied low voltage and driving control signals, and then, alternating and outputting a number of high-powered signals. Therefore, the driver chip has a small number of wirings at a part connected to the driving substrate 230 and a relatively large number of wirings at the other part connected to the panel 220.

The wiring of the driver chip 241 may be connected through a space formed at the driving substrate side. The wiring 243 may not be defined by a barrier based on the center of the driver chip 241.

FIG. 6 is a schematic view illustrating a plasma display device according to another exemplary embodiment of the present invention.

In an exemplary embodiment of the present invention, the panel 220 is connected to the driving device through a flexible printed circuit (hereinafter, referred to as "FPC") 250.

The FPC 250 is a film having a pattern formed therein using polyimide. The FPC 250 and the panel 220 are connected to each other by the ACF. The driving substrate 230 used in this embodiment is a PCB.

The driving device may include a data driver, a scan driver and/or a sustain driver.

The data driver is connected to the address electrode to apply data pulses thereto. Likewise, the scan driver is connected to the scan electrode to provide Ramp-up and/or Ramp-down waveforms, scan pulse and sustain pulse thereto. In addition, the sustain driver applies sustain pulse and DC voltage to a sustain common electrode.

Driving operation of the plasma display panel is divided into three periods, that is, a reset period, an address period and a sustain period.

During the reset period, a Ramp-up waveform is simultaneously applied to plural scan electrodes. During the address period, a negative scan pulse is applied to the scan electrodes in order while synchronizing with a scan pulse to apply a positive data pulse to plural address electrodes in sequence. Lastly, a sustain pulse is alternately applied to the scan electrodes and the sustain electrodes during a sustain period.

Hereinafter, the plasma display panel of the present invention will be described in greater detail in the following description of examples with reference to the accompanying drawings.

[First Embodiment]

FIGs. 7 to 9 are schematic views sequentially illustrating a process for fabricating a front substrate of a plasma display device according to an exemplary embodiment of the present invention.

In the first embodiment, a protective film 195 containing zeolite disclosed above was formed, wherein the zeolite improves film characteristics of the protective film 195 so as to reduce a firing voltage of a PDP while improving luminance and emission efficiency thereof.

Referring to FIGs. 7 to 9, a process for fabricating a front substrate 170 of a plasma display panel according to the first embodiment will be described in detail.

Firstly, as illustrated in FIG. 7, a scan electrode 180a, a sustain electrode 180b and bus electrodes 180a' and 180b' are formed on the front substrate 170.

The front substrate 170 may be fabricated by milling a glass for a display substrate or a soda lime glass, and then, cleaning the same.

The scan electrode 180a and the sustain electrode 180b may be formed by photo-etching ITO through sputtering.

Alternatively, the scan electrode 180a and the sustain electrode 180b may be formed by ion plating ITO or vacuum deposition thereof.

The scan electrode 180a and the sustain electrode 180 may also be formed using SnO ₂ by a lift-off process through CVD.

As for the photo-etching of ITO to form the scan electrode 180a and the sustain electrode 180b, the ITO is deposited on the front substrate 170. Next, photoresist is applied to the deposited ITO, followed by drying the photoresist coated ITO. Placing a patterned photo-mask on the photoresist and irradiating light, the photoresist is exposed. After exposure, the uncured part is developed and etched to form the scan electrode 180a and the sustain electrode 180b.

As for the lift-off process of SnO ₂ to form the scan electrode 180a and the sustain electrode 180b, after photoresist is applied to the front substrate 170, placing a patterned photo-mask on the applied photoresist and irradiating light, the photoresist is exposed. After exposure, the uncured part is developed. After the developing process, SnO ₂ is deposited to the front substrate and the photoresist is released, thus forming the scan electrode 180a and the sustain electrode 180b.

Each of the scan electrode 180a and the sustain electrode 180 may have a black matrix, which includes a low melting point glass and a black pigment.

The bus electrodes 180a' and 180b' may be formed using Ag by screen printing or a photosensitive paste method.

Alternatively, the bus electrodes 180a' and 180b' may be formed by photo-etching Cr/Cu/Cr or Cr/Al/Cr through sputtering.

As for the screen printing to form the bus electrodes 180a' and 180b' a conductive paste such as Ag is printed on the front substrate 170 through a screen mask, followed by drying and firing the processed front substrate to form the bus electrodes.

As for the photosensitive paste method to form the bus electrodes 180a' and 180b' photosensitive Ag is printed and applied to the front substrate 170, followed by drying the processed front substrate. After that, placing a patterned photo-mask on the Ag coating and irradiating light, the Ag coating is exposed. After exposure, the uncured part is developed. After the developing process, the resultant substrate is dried and fired, thus forming the bus electrodes 180a'and 180b'

As for the photo-etching process to form the bus electrodes 180a' and 180b' Cr/Cu/Cr or Cr/Al/Cr is deposited on the front substrate 170 and photoresist is applied to the deposited Cr/Cu/Cr or Cr/Al/Cr, followed by drying the same. After that, placing a patterned photo-mask on the photoresist and irradiating light, the photoresist is exposed. After the exposure, the uncured part is developed and etched to form the bus electrodes 180a'and 180b'

The scan electrode 180a, the sustain electrode 180b and the bus electrodes 180a' and 180b' are substantially discharge electrodes, therefore, the plasma display panel of the present invention may include the discharge electrode consisting of only the bus electrodes 180a'and 180b' without the scan electrode 180a and the sustain electrode 180b.

Subsequently, as illustrated by FIG. 8, a first dielectric layer 190 is formed on the front substrate 170 on which the scan electrode 180a, the sustain electrode 180b and the bus electrodes 180a' and 180b' are formed.

The first dielectric layer 190 may be formed using a low melting point glass by screen printing, use of a coater, and/or lamination of a green sheet.

The coater may be a roll or a slot.

Following this, as illustrated in FIG. 9, a protective film according to the present invention is formed on the first dielectric layer 190.

Hereinafter, a detailed description will be given of a process for fabrication of the protective film 195 by separately forming a first layer containing MgO and a second layer containing zeolite.

Firstly, as illustrated in FIG. 9, the first layer 196 is formed on the first dielectric layer 190.

Here, MgO with excellent orientation and crystalline properties may be laminated in a thin film form thereon, in order to increase a film density of the protective film 195 and improve anti-sputtering properties thereof. In order to enhance film characteristics of the protective film as described above, a certain amount of dopant may be added thereto wherein the amount is of course within the range of 0.001 to 10 wt.% in the first layer 196.

More particularly, after preparing an MgO containing material, the material is deposited on the first dielectric layer 190. Next, the first layer 196 is subjected to drying and firing processes. Such firing process may be performed simultaneously with the firing process for the second layer 198.

Deposition of the first layer material may be performed by any typical process including, for example, green sheet lamination, chemical vapor deposition, electron beam (E-beam) deposition, sputtering and/or ion plating.

Such E-beam deposition is a method of forming a protective film by inducing E-beam collision to a protective film material, evaporating and diffusing the collided material and depositing the diffused material on an upper plate dielectric layer to produce the protective film. Concentrating E-beam energy upon a target surface may attain fast deposition and enable formation of a high purity protective film.

Meanwhile, ion plating generally means a combination of vacuum deposition and sputtering and may be used to form a protective film by generating plasma through glow discharge, which occurs by application of a high voltage under ultra-high vacuum, and ionizing some of the vaporized atoms.

Then, the second layer 198 containing zeolite is formed on the first layer 196.

Characteristics of the zeolite used herein are shown in Formula 1. The second layer 198 is preferably laminated in a thin film form on the first layer 196. Deposition of the second layer 198 may be performed by any typical process including, for example, spray coating, bar coating, blade coating, spin coating, an ink-jet method and/or a green sheet method.

A solution containing the second layer material is prepared because a liquid method is economically advantageous and needs relatively simple processing.

Firstly, a solvent, a dispersant and an organic binder are premixed together. The solvent may be any one selected from alcohol, ketone, ester, glycol ester and water (H ₂ O). Zeolite with a uniform size is prepared for use by grinding a zeolite raw material then size separating the ground zeolite. The premixed material is mixed with the prepared zeolite to produce a mixture solution.

The mixture solution is applied to the first layer 196 to form a laminate by any lamination process such as spray coating, table coating, dispensing or printing. In case where the material is prepared in a green sheet form, a green sheet laminate may be formed using a roller.

Next, drying and firing processes are performed. In this case, conditions for such drying and firing processes may be varied depending on kinds and/or contents of the solvent, dispersant and organic binder. In general, the drying process is executed at 50 to 250℃ while the firing process is performed at 250 to 650℃.

Hereinafter, functional effects of the fabricated protective film containing zeolite were compared according to the following Comparative Example.

[COMPARATIVE EXAMPLE]

A solution containing MgO is prepared. A dispersant and an organic binder are premixed in a solvent selected from alcohol, ketone, ester, glycol ester and water.

MgO powder with a uniform size is prepared for use by grinding an MgO raw material then size separating the ground MgO. The premixed material is mixed with the prepared MgO powder to produce a mixture solution.

The mixture solution is applied to an upper plate dielectric layer by spraying, followed by drying at 100℃ and firing the same at 550℃.

[EXAMPLE 1]

A dispersant and an organic binder are premixed in a solvent selected from alcohol, ketone, ester, glycol ester and water. MgO powder with a uniform size is prepared for use by grinding an MgO raw material then size separating the ground MgO. The premixed material is mixed with the prepared MgO powder to produce a mixture solution.

Next, after grinding and size separating zeolite y, the prepared zeolite y is added to the mixture solution. Here, a content of the zeolite y is about 1,000ppm in the solution. The mixture solution is applied to an upper plate dielectric layer by spraying, followed by drying at 100℃ and firing the same at 550℃.

[EXAMPLE 2]

A dispersant and an organic binder are premixed in a solvent selected from alcohol, ketone, ester, glycol ester and water. MgO powder with a uniform size is prepared for use by grinding an MgO raw material then size separating the ground MgO. The premixed material is mixed with the prepared MgO powder to produce a mixture solution.

Next, after grinding and size separating zeolite x, the prepared zeolite x is added to the mixture solution. Here, a content of the zeolite x is about 1,000ppm to the solution. The mixture solution is applied to an upper plate dielectric layer by spraying, followed by drying at 100℃ and firing the same at 550℃.

[EXAMPLE 3]

A dispersant and an organic binder are premixed in a solvent selected from alcohol, ketone, ester, glycol ester and water. MgO powder with a uniform size is prepared for use by grinding an MgO raw material then size separating the ground MgO. The premixed material is mixed with the prepared MgO powder to produce a mixture solution.

Next, after grinding and size separating ZSM-5, the prepared ZSM-5 is added to the mixture solution. Here, a content of the added ZSM-5 is about 1,000ppm in the solution. The mixture solution is applied to an upper plate dielectric layer by spraying, followed by drying at 100℃ and firing the same at 550℃.

The following Table 1 comparably shows discharge voltage characteristics, firing voltages, luminance and emission efficiencies of the protective films prepared in Comparative Example and Examples 1 to 3.

Table 1

From Table 1, 'First On' is a voltage when a discharge cell was firstly turned on and 'Full On' is a voltage when all discharge cells were turned on. Likewise, 'Fast Off' is a voltage when a discharge cell was firstly turned off while 'Full Off' is a voltage when all discharge cells were turned off. 'Vt' means a firing voltage indicated on a 'Vt' graph.

As shown in Table 1, it is understood that a plasma display panel having the protective film, which was prepared by adding zeolite to a protective film material and was applied to the panel by spraying according to each of the foregoing examples, exhibits superior discharge voltage characteristics over a plasma display panel having the protective film containing MgO only prepared in the above comparative example.

Likewise, as for luminance and emission efficiency, it can be seen that the plasma display panels prepared in the examples are higher than 100% of the plasma display panel prepared in the comparative example. That is, since zeolite can complement defects of MgO in that MgO is easily affected by moisture and damaged by radical ions, using zeolite may prevent damage of a protective film in the plasma display panel during etching of a barrier rib and/or a firing process, thereby attaining functional effects disclosed above.

As is apparent from the above description, the first embodiment of the present invention provides the protective film 195 containing zeolite with improved film characteristics thereof, so that a PDP having the protective film may exhibit reduced firing voltage and enhanced luminance and emission efficiency.

[Second Embodiment]

FIGs. 10 to 16 are schematic views sequentially illustrating a process for fabricating a back substrate of a plasma display device according to an exemplary embodiment of the present invention.

Firstly, as illustrated in FIG. 10, an address electrode 120 is formed on a back substrate 110. The back substrate 110 may be fabricated by milling and/or cleaning a glass for a display substrate or a soda lime glass.

The address electrode 120 may be formed using Ag by screen printing or a photosensitive paste method.

Alternatively, the address electrode 120 may be formed by photo-etching Cr/Cu/Cr or Cr/Al/Cr through sputtering.

In this regard, as for the screen printing to form the address electrode 120, a conductive paste such as Ag is printed on a back substrate 110 through a screen mask, followed by drying and firing the back substrate to form the address electrode.

As for the photosensitive paste method to form the address electrode 120, photosensitive Ag is printed and applied to the back substrate 110, followed by drying the back substrate. After that, placing a patterned photo-mask on the Ag coating and irradiating light, the Ag coating is exposed. After exposure, the uncured part is developed. After the developing process, the resultant substrate is dried and fired, thus forming the address electrode 120.

In addition, as for the photo-etching process to form the address electrode 120, Cr/Cu/Cr or Cr/Al/Cr is deposited on the back substrate 110. Photoresist is applied to the deposited Cr/Cu/Cr and Cr/Al/Cr, and then, is dried. Next, placing a patterned photo-mask on the photoresist and irradiating light, the photoresist is exposed. After exposure, the uncured part is developed and etched, thus forming the address electrode 120.

Referring to FIG. 11, the second dielectric layer 130 containing zeolite and nanometal oxide according to the second embodiment of the present invention is formed on an address electrode 120.

Hereinafter, a detailed description will be given of a method for formation of the second dielectric layer 130 with reference to a green sheet lamination process as an exemplary embodiment of the present invention.

As shown in FIG. 11, a second dielectric layer material 130a is prepared.

Such material 130a may comprise a low-melting point glass 132, a filler 134, zeolite 136 and nanometal oxide 138. Although not shown in the drawing, the second dielectric layer material may further include organic substances including, for example, a solvent, a dispersant and an organic binder. Such solvent may be selected from alcohol, ketone, ester, glycol ester and water.

Firstly, the dispersant and the organic binder are premixed in the solvent. After grinding the low-melting glass 132 and the filler 134, the zeolite 136 and the nanometal oxide 138 are mixed with the premixed material to prepare a paste. Here, each of the low-melting point glass 132 and the filler 134 is size separated to have a uniform size. The low-melting point glass 132 may be either lead containing parent glass or unleaded parent glass.

The lead containing parent glass may comprise ZnO, PbO and B ₂ O ₃ , while the leaded parent glass may comprise ZnO, B ₂ O ₃ , BaO, SrO and CaO. The filler 134 may include carbon compounds such as SiC, nitrogen compounds such as BN, carbon nanotubes, and the like.

Constitutional compositions and characteristics of the zeolite 136 and the nanometal oxide 138 are shown in the above Formula 1.

The second dielectric layer material 130a prepared in a paste form according to the procedure disclosed above is applied by printing or green sheet laminating, then, is subjected to drying and firing processes.

FIG. 11 illustrates a process of laminating the second dielectric layer material 130a in the form of a green sheet.

As shown in FIG. 11, the green sheet type second dielectric layer material 130a is interposed between a base film 'a' and a cover film 'b'.

While removing the base film 'a' the cover film 'b' is rolled using a roller 131 so as to press the second dielectric layer material 130a on a back substrate 110. Then, after removing the cover film 'b' the drying and firing processes are performed. These processes may be carried out simultaneously with the firing process for a barrier rib and a back plate dielectric layer described below.

The drying serves to remove a part of the organic substance such as the solvent and may be executed at about 100℃, while the firing process serves to completely burn off the same organic substance and may be performed at 520 to 550℃. After the drying and firing processes, the second dielectric layer 130 contains only the low-melting point glass 132, the filler 134, the zeolite 136 and the nanometal oxide 138 remained therein, as shown in FIG. 12.

The zeolite 136 is not expensive, exhibits favorable heat resistance and has fine pores on a molecular scale, thus having a large surface area and adsorbing large amounts of gas impurities per unit volume.

The zeolite used herein may be cation-exchange type zeolite to selectively adsorb and decompose impure gas. Applying such characteristics of the zeolite may easily adsorb and decompose ions, radical moistures and impure gas contained in a discharge cell. In this case, such impure gas in the discharge cell may include carbon dioxide, water, hydrocarbon, etc.

Impurities including ions may react with the phosphor material after firing, thus, may be evaporated by increased temperature in the discharge cell or high energy excitation when the display panel is driven for a long period of time, so that the evaporated material may pollute the discharge gas.

However, according to the exemplary embodiment of the present invention, a porous material such as the zeolite 136 may serve as an adsorption layer to adsorb the gas impurities and/or moisture.

Accordingly, it is possible to prevent pollution of a discharge space caused by impure gas and/or moisture therein so that deterioration of phosphor or discharge gas may be prevented, thereby inhibiting reduction of luminance and emission efficiency while increasing discharge efficiency, and improving lifespan and reliability of a display panel.

In addition, these functional effects may be remarkably enhanced using the nanometal oxide 138 as well as the zeolite 136. Briefly, both the zeolite 136 and the nanometal oxide 138 may promote adsorption of organic substances or residual coal and pyrolysis thereof, so as to improve reflectivity and luminance of a white dielectric layer 130.

In order to achieve such effects, the second dielectric layer material 130a may contain 0.001 to 10 wt.% of zeolite 136 and 0.001 to 10 wt.% of nanometal oxide 138.

Here, a relative ratio by weight of the zeolite 136 to the nanometal oxide 138 may be 1∼60% to 40∼99%.

[Third Embodiment]

Continuously, a barrier rib 140 for isolating individual discharge cells is formed as shown in FIGs. 13 to 15.

According to the third embodiment of the present invention, a barrier rib material 140a may comprise a parent glass 141, a filler 142, zeolite 143 and nanometal oxide 144.

The parent glass 141 may comprise PbO, SiO ₂ , B ₂ O ₃ and Al ₂ O ₃ while the filler 142 may comprise TiO ₂ and Al ₂ O ₃ . However, in consideration of environmental regulations, alternative substances not containing Pb may be used.

Kinds and constitutional compositions of the zeolite 143 and the nanometal oxide 144 may be substantially the same as disclosed in the second embodiment.

The barrier rib material 140a preferably contains 0.001 to 10 wt.% of zeolite 143 and 0.001 to 10 wt.% of nanometal oxide 144.

Also, a relative ratio by weight of the zeolite 143 to the nanometal oxide 144 may be 1∼60% to 40∼99%. Within these ranges, the zeolite 143 and the nanometal oxide 144 may exhibit maximal impurity adsorption and maximal impurity decomposition, respectively.

Application of the barrier rib material may be conducted by green sheet lamination, and/or table coating, dispensing or printing of a paste, and so forth. Hereinafter, paste coating and patterning processes will be described in detail as an exemplary embodiment of the present invention.

Firstly, as shown in FIG. 13, the barrier rib material 140a is applied to the second dielectric layer 130. As disclosed above, such barrier rib material 140a may include the zeolite 143 and the nanometal oxide 144 in addition to general materials. The barrier rib material may comprise of course other organic substances such as a binder, a dispersant and a solvent.

Referring to FIG. 14, the barrier rib material 140a is patterned into a barrier rib. Such patterning may be performed by covering the barrier rib material with a mask, exposing the mask and developing the same. More particularly, the mask 145 is placed on a part of the barrier rib material corresponding to an address electrode and exposed to light, followed by developing and firing the same. As a result, a light irradiated part remains only in the form of a barrier rib. If the barrier rib material 140a contains a photoresist ingredient, the patterning is easily conducted.

Next, drying and firing the patterned material may result in a complete barrier rib 140 as shown in FIG. 15. The drying process serves to remove a part of the organic substance such as the solvent and may be executed at about 100℃, while the firing process serves to completely burn off the same organic substance and may be performed at 520 to 550℃. After the drying and firing processes, the barrier rib 140 contains only the low-melting point glass 141, the filler 142, the zeolite 143 and the nanometal oxide 144 remained therein, as shown in FIG. 15.

As is apparent from the above description, the zeolite 143 may easily adsorb and decompose ions, radical moisture and/or impure gas contained in the discharge cell. Such impure gas may include carbon monoxide, carbon dioxide, water, hydrocarbon, etc.

Impurities such as ions may react with the phosphor material after firing and this may be evaporated by increased temperature in the discharge cell or high energy excitation when the display panel is driven for a long period of time, so that the evaporated material may pollute the discharge gas.

However, according to the exemplary embodiment of the present invention, a porous material such as the zeolite 143 may serve as an adsorption layer to adsorb the impure gas and/or moisture.

Accordingly, it is possible to prevent pollution of a discharge space caused by impure gas and/or moisture therein so that deterioration of the phosphor or discharge gas may be prevented, thereby inhibiting reduction of luminance and emission efficiency while increasing discharge efficiency, and improving lifespan and reliability of a display panel.

In addition, these functional effects may be remarkably enhanced using the nanometal oxide 144 as well as the zeolite 143. Briefly, both the zeolite 143 and the nanometal oxide 144 may promote adsorption of organic substances or residual coal and pyrolysis thereof, so as to improve reflectivity and luminance of the barrier rib 140.

[Fourth Embodiment]

As shown in FIG. 16, a region adjacent to the discharge space among overall region of the second dielectric layer 130 and a lateral side of the barrier rib 140 are coated with phosphor material 151 to form a phosphor layer 150.

In this case, the phosphor layer 150 may comprise red, green and blue phosphor materials (R, G, B) 151, 0.001 to 10 wt.% of zeolite 152 and 0.001 to 10 wt.% of nanometal oxide 153.

The phosphor layer 150 may be coated with R, G and B phosphor materials in sequential order depending on respective discharge cells by screen printing or a photosensitive paste method.

Mostly, the red phosphor material R comprises (Y, Gd)BO ₃ :Eu3 ⁺ , the green phosphor material G comprises Zn ₂ SiO ₄ :Mn2 ⁺ , and the blue phosphor material B comprises BaMgAl ₁₀ O ₁₇ :Eu2 ⁺ .

As disclosed above, a paste including the phosphor material 151 together with 0.001 to 10 wt.% of zeolite 152 and 0.001 to 10 wt.% of nanometal oxide 153 is applied to the discharge cells isolated by the barrier rib 140, then, is subjected to drying and firing to complete formation of the phosphor layer 150 containing the zeolite 152 and the nanometal oxide 153 according to the fourth embodiment of the present invention.

FIG. 17 is a graph comparably illustrating pyrolysis temperatures and residual organic matters between a conventional phosphor layer and a phosphor layer according to the present invention.

FIG. 18 is a graph comparably illustrating optical properties between a conventional phosphor layer and a phosphor layer according to the present invention.

That is, the phosphor layer 150 according to the fourth embodiment of the present invention has lower organic residue after firing than the conventional layer, so as to efficiently alleviate a decrease in luminance and/or emission efficiency of the phosphor layer caused by adsorption of organic materials to a surface of the phosphor layer.

More particularly, the organic binder is decomposed by heat during the firing process and the zeolite 152 and the nanometal oxide 153 may be activated by strong heat to accelerate decomposition of the organic materials, thereby improving characteristics of the phosphor layer over the conventional phosphor layer.

Referring to FIG. 17, as a result of comparing ethyl cellulose (EC) contained in the conventional phosphor layer with materials contained in a first phosphor layer (acrylate + zeolite + Al ₂ O ₃ TiO ₂ ) and materials contained in a second phosphor layer (acrylate + zeolite + Al ₂ O ₃ TiO ₂ ) according to the fourth embodiment of the present invention, it was found that the first and second phosphor layers of the present invention have faster pyrolysis starting temperature and lower content of organic residue than the conventional phosphor layer.

Referring to FIG. 18, as a result of comparing the first and second phosphor materials of the present invention with the conventional phosphor layer by a PL apparatus after the phosphor materials were applied to the discharge space in the barrier rib and fired, it was found that the first and second phosphor layers have superior luminance and emission efficiency over the conventional phosphor layer while showing substantially neither yellowing nor color change.

Next, the front substrate 170 completed by a process illustrated in FIG. 7 to 9 is adhered and sealed to the back substrate 110 by interposing the barrier rib 140 therebetween. After removing impurities from the substrates, Xe + Ne, Xe + He or Xe + Ne + He discharge gas is introduced to discharge cells in the barrier rib 140, followed by sealing so as to complete a plasma display panel as shown in FIG. 1 according to the present invention.

The following description will be given of a sealing process of the front substrate 170 and the back substrate 110.

The sealing process may commonly be conducted by screen printing or a dispensing method.

As for the screen printing, a patterning screen is placed a certain distance above a substrate, a paste forming a sealant is pressed on the screen to be transcribed, so as to print the sealant in a desired shape. The screen printing has merits of using a simple production system and high use efficiency of raw materials.

As for the dispensing method, using CAD wiring data typically used for manufacture of a screen mask, a thick film paste is directly injected over a substrate under air pressure so as to form a sealant. The dispensing method is advantageous in that production costs of a mask are reduced and the thick film has a high degree of freedom in shaping.

FIG. 19 illustrates a process of combining a front substrate with a back substrate of a plasma display panel.

FIG. 20 is a cross-sectional view taken along the line A-A'of FIG. 19.

As illustrated in these figures, a sealant 600 is applied to the front substrate 170 and the back substrate 110. More particularly, simultaneously printing or dispensing the sealant at a certain distance from the outermost side of each substrate, the sealant is applied to the substrates.

Continuously, the sealant is subjected to firing. During firing, organic materials contained in the sealant are removed and the front substrate 170 is combined with the back substrate 110.

During firing, a width of the sealant 600 may be increased while a thickness of the sealant may be reduced.

Although the sealant 600 is printed or coated according to the exemplary embodiments disclosed above, the sealant may be adhered to the front substrate 170 or the back substrate 110 in the form of a sealing tape. Additionally, an ageing process is performed at a desired temperature so as to improve characteristics of the protective film.

A front filter may be formed on the front substrate 170.

The front filter may have an electromagnetic interference (EMI) shielding film to prevent EMI from being emitted from the display panel. Coating the front filter with a conductive material patterned in a specific form, the front filter may ensure high visible light transmittance required for a display device while shielding EMI.

In addition, the front filter may have a near-infrared shielding film, a color compensation film and/or an anti-reflection film.

Although technical constructions and other features of the present invention have been described, it will be apparent to those skilled in the art that the present invention is not limited to the exemplary embodiments and accompanying drawings described above but may cover substitutions, variations and/or modifications thereof without departing from the sprit or scope of the invention.

Accordingly, the present invention is not restricted to the contents illustrated in the above description but is construed to come within the scope of the invention defined in the appended claims and their equivalents.